Electronic-optical imaging and detection systems are increasingly used in a variety of different applications. Such systems include infrared image intensifiers which are used to enhance night vision capabilities in extreme low light conditions. Such intensifiers are employed in conjunction with binoculars, night vision goggles, and in other applications. Electronic multiplex video cameras also utilize light sensitive components which react to the intensity of the light directed toward the camera for controlling the camera lens opening. Similar circuits also are provided for "automatic" 35MM cameras.
Sensitive thermal imagers currently being developed may be used in some applications in a manner similar to image intensifiers for providing a visual output based on a thermal pattern. Devices of this type may be substituted for or may be used in conjunction with infrared imager intensifiers for improved night vision applications.
Image intensifiers, electronic multiplex cameras, and thermal imagers of the type mentioned above all include relatively sensitive receiving components which are vulnerable, at least to some degree, to differing levels of damage from exposure to strong light sources, such as lasers, directed into the field of view of the devices. With the proliferation of laser systems (such as range finders, infrared illuminators and the like), image detecting systems, image intensifiers, thermal imagers and electronic cameras of the type mentioned above require some type of protection against damage from such strong light sources.
Consequently, it is desirable to provide a safety protection system for a light sensitive electronic/optical system or thermal imager capable of intercepting impinging light energy which has an intensity in excess of a safe threshold to shut down or turn off the system to prevent damage to it.